I have read quite a few threads on here about these misfiring issues, which have taught me a lot about the issues and helped a lot. But, I couldn't find anything about my exact problem, which is getting very irritating. A couple months ago the first misfire happened in coil number 4, we fixed it ourselves and all seemed fine. Then about 3 weeks ago another misfire happened in coil 2 and 5. We then replaced ever coil and plug to get it all done at once. All seemed fine again and everything checked out. Then once again, last week a misfire in the first coil happened again. We are just baffled as to why it would happen over and over. Could there be anything wrong that would be causing it to misfire? Voltage problems or electrical problems? Any help or suggestions would be greatly appreciated!

 

What codes were received each time?

What plugs are you using? Aftermarket? Same as original?

Same for coils? Aftermarket? Same as original?

FYI - I have a post about the same problem (only once though). The dealer told me yesterday that coils going bad are a very common problem.

 

The latest code was PO301 B I believe. We did consider the coils may have been bad, but just didn't think that would happen after only a week. The coils are all Standard brand, which we were told to be reliable and affordable. The plugs are all Motorcraft. Do you think any of those could just be unreliable and failed already?

 

What does the "B" mean on the code? Cyl #1 misfire what?

I really don't know. I asked because I've read a lot online too trying to work out my problem. I will be using all Ford parts. They will be here tomorrow, so in 8 days I can tell you if I have the problem again. I'm also reading dielectric (spelling?) grease should be used.

I used a spark tester to verify the coils identified from the codes were indeed bad. I also switched a bad coil with a good one to see if the problem moved (it did).

One of us here is a dealer parts manager. Standard is a pretty good aftermarket brand.

 

In researching your problem, I found this article. I thought it summarized all my research very well although for older technology (same principles, just test differently). FYI - In my post (separate post), the coil test didn't ID my problem.

How to Diagnose and Test an Ignition Coil

 

haven been a dealer mechanic.bad coils are problems and it is not uncommon to have many go bad repeatitly. one reason while costly it is some times best to have a dealer check and repair these problems only as they input the information into the national dealer data base and warrenty the part and work normally for a year or 12k miles.
then if you have a problem of he same issue say 3 months down the line and several hundred miles from home,your six is covered for parts and labor.

if one handles the repair on his or her own use only a factory part and keep the receipt close by should that part again fail. again normally the warrenty is 12k x 12 months